Following neonatal jaundice, the facts concerning subsequent child development including possible cerebral dysfunction have not been easy to define. A searching examination of morphological and behavioral changes - including hypothesized recovery processes - after hyperbilirubinemia, are planned under controlled laboratory conditions. A hyperbilirubinemic mutant rat (Gunn rat) will be the animal model used for (1) fundamental studies and (11) testing and comparing the effectiveness of therapeutic procedures. 1. FUNDAMENTAL STUDIES. In correlated behavioral and biostructural experiments, the effects of bilirubin toxicity on development of brain structure and function will be explored. Behavioral tasks will be used to detect deficits in learning ability, hearing, motor activity and "emotionality". Structural damage to functionally important brain structures will be evaluated, and fluorescence microscopy will be used to investigate effects of hyperbilirubinemia on catecholamine systems. Quantitative studies of neuron numbers and synapse formation (numbers and development) will be carried out, with particular attention being paid to eliciting evidence regarding recovery. 2. THERAPEUTIC STUDIES. In related experiments, the same technical procedures will be used to evaluate and compare the effectiveness of various treatments (including phototherapy, albumin, and prednisolone administration) in ameliorating behavioral and biostructural abnormalities that occur in the homozygous Gunn rat brain.